The present invention relates to implantable stimulator systems, and more particularly to an implantable stimulator system utilizing one or more implantable microstimulators for treating incontinence and/or pain.
Urinary Incontinence is a clinical condition characterized by failure to hold urine in the bladder under normal conditions of pressure and filling. The most common forms of the disorder can arise from either a failure of muscles around the bladder neck and urethra to maintain closure of the urinary outlet (so-called stress incontinence) or from abnormally heightened commands from the spinal cord to the bladder that produce unanticipated bladder contractions (so-called urge incontinence). Many patients exhibit a grouping of symptoms suggesting that these disorders may occur simultaneously in the same individual (so-called mixed incontinence).
It is well known in the art that electrical stimulation in the region of the pelvic floor can decrease the severity of incontinence. The improvement is believed to be attained through at least three mechanisms: (1) by changing the reflex thresholds of the bladder muscles responsible for bladder emptying, (2) by strengthening the muscles that maintain closure on the bladder outlet, and (3) by changing the state of the neural pathways, musculature and/or bladder during and beyond the period of stimulus application.
The therapies currently available for incontinence have generally been directed at improving muscle condition, as disclosed, e.g., in applicant""s prior document WO97/18857 (PCT/US96/18680), published May 29, 1997. Bladder hyper-reflexia and detrusor instability have proven more difficult to treat. However, evidence in the art suggests that it can be improved in many individuals by stimulating peripheral nerves or nerve roots continuously or intermittently to modulate transmission of excitatory nerve signals to the bladder muscles.
Several external and implantable approaches have been used to stimulate the nerves supplying the bladder and pelvic region in order to decrease the episodic incidences of unintentional bladder emptying. Those who strengthen periurethral muscles have usually employed vaginal or anal electrode assemblages to stimulate muscle contractions repeatedly. These methods are limited in their portability and are often poorly accepted by patients because they are inconvenient and often associated with unpleasant skin sensations. Further, the methods are inadequate for the treatment of urge incontinence in which continual electrical stimulation is commonly needed to diminish or inhibit the heightened reflexes of bladder muscles.
For the treatment of urge incontinence, surgically implanted stimulators under battery or radio-frequency control have been described in the art. These stimulators have different forms, but are usually comprised of an implantable control module to which is connected a series of leads that must be routed to nerve bundles in either the sacral roots emanating from the spinal cord, or the nerves supplying muscles, skin or other structures in the pelvic region. The implantable devices are relatively large, expensive and challenging to implant surgically. Thus, their use has generally been confined to patients with severe symptoms and the capacity to finance the surgery.
These same types of therapies have been used to treat pelvic pain, with the same drawbacks. For instance, neurostimulation of the sacral nerve roots has been demonstrated to relieve pelvic pain in patients with intractable chronic pelvic pain. Other devices used for both incontinence and pelvic pain require that a needle electrode(s) be inserted through the skin during stimulation sessions. These devices may only be used acutely, and may cause significant discomfort.
More recently, small, implantable microstimulators have been introduced that can be injected into soft tissues through a cannula or needle. See, e.g., U.S. Pat. Nos. 5,324,316 and 5,405,367, both of which patents are incorporated herein by reference. What is needed is a way to effectively use such small, implantable microstimulators for the purpose of treating incontinence and/or pelvic pain.
The system and method taught in this invention include the injection, direct implantation, endoscopic, or laparoscopic implantation of one or more battery- or radio-frequency-powered microstimulators beneath the skin of the perineum. The system and method taught also include the injection, direct implantation, endoscopic, or laparoscopic implantation of one or more battery- or radio-frequency-powered microstimulators on or near the tibial nerve. The devices are programmed using radio-frequency control via an external controller that can be used by a physician to produce patterns of output stimulation pulses judged to be efficacious by appropriate clinical testing. Such stimulation program is retained in the device or external controller and is transmitted when commanded to start and stop by a signal from the patient or caregiver.
It is an object of this invention to reduce or eliminate the incidence of unintentional episodes of bladder emptying (i.e. incontinence) as well as other dysfunctions of perineal structures, such as urgency and frequency by stimulating nerve pathways that diminish involuntary bladder contractions, improve closure of the bladder outlet, and/or improve the long-term health of the urinary system by increasing bladder capacity and thus, the time period between emptying. As one example of another dysfunction of perineal structures, it is also an object of this invention to similarly reduce or eliminate the incidence of fecal incontinence.
Another object of this invention is to reduce or eliminate pelvic pain by chronically stimulating nerve pathways that derive from the sacral roots using an implantable neurostimulator that is implanted with a minimal surgical procedure.
It is a further object of this invention to teach a method whereby a patient can receive one or more patterns of neural stimulation that can be prescribed by a physician and administered without continuous oversight by a clinical practitioner.
It is a feature of the invention to meet the above-identified objects of the invention using a system of small, implantable microstimulators of the type described in, or similar to those described in, the above-referenced patents and/or patent applications.